High-momentum top quarks are a natural physical system in collider experiments for testing models of new physics, and jet substructure methods are key both to exploiting their largest decay mode and to assuaging resolution difficulties as the boosted system becomes increasingly collimated in the detector. To be used in new-physics interpretation studies, it is crucial that related methods get implemented in analysis frameworks allowing for the reinterpretation of the results of the LHC such as MadAnalysis 5 and Rivet. We describe the implementation of the HEPTopTagger algorithm in these two frameworks, and we exemplify the usage of the resulting functionalities to explore the sensitivity of boosted top reconstruction performance to new physics contributions from the Standard Model Effective Field Theory. The results of this study lead to important conclusions about the implicit assumption of Standard-Model-like top quark decays in associated collider analyses, and for the prospects to constrain the Standard Model Effective Field Theory via kinematic observables built from boosted semi-leptonic  $$t\bar{t}$$  <math> <mrow> <mi>t</mi> <mover> <mrow> <mi>t</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> </mrow> </math>   events selected using HEPTopTagger.

United Kingdom

Jack Araz

Andy Buckley

France

Benjamin Fuks

Searches for new physics with boosted top quarks in the MadAnalysis 5 and Rivet frameworks

Using the GAMBIT global fitting framework, we constrain the MSSM with an eV-scale gravitino as the lightest supersymmetric particle, and the six electroweakinos (neutralinos and charginos) as the only other light new states. We combine 15 ATLAS and 12 CMS searches at 13 TeV, along with a large collection of ATLAS and CMS measurements of Standard Model signatures. This model, which we refer to as the  $${{\tilde{G}}}$$  <math> <mover> <mi>G</mi> <mo>~</mo> </mover> </math>  -EWMSSM, exhibits quite varied collider phenomenology due to its many permitted electroweakino production processes and decay modes. Characteristic  $${{\tilde{G}}}$$  <math> <mover> <mi>G</mi> <mo>~</mo> </mover> </math>  -EWMSSM signal events have two or more Standard Model bosons and missing energy due to the escaping gravitinos. While much of the  $${{\tilde{G}}}$$  <math> <mover> <mi>G</mi> <mo>~</mo> </mover> </math>  -EWMSSM parameter space is excluded, we find several viable parameter regions that predict phenomenologically rich scenarios with multiple neutralinos and charginos within the kinematic reach of the LHC during Run 3, or the High Luminosity LHC. In particular, we identify scenarios with Higgsino-dominated electroweakinos as light as 140 GeV that are consistent with our combined set of collider searches and measurements. The full set of  $${{\tilde{G}}}$$  <math> <mover> <mi>G</mi> <mo>~</mo> </mover> </math>  -EWMSSM parameter samples and GAMBIT input files generated for this work is available via Zenodo.

Norway

Viktor Ananyev

Australia

Csaba Balázs

Ankit Beniwal

Lasse Braseth

Jonathan Butterworth

Christopher Chang

Canada

Matthias Danninger

China

Andrew Fowlie

Germany

Tomás Gonzalo

Anders Kvellestad

CERN

Farvah Mahmoudi

United States

Gregory Martinez

Markus Prim

Tomasz Procter

Are Raklev

Pat Scott

Patrick Stöcker

Jeriek Abeele

Martin White

Yang Zhang

Collider constraints on electroweakinos in the presence of a light gravitino

Poor computing efficiency of precision event generators for LHC physics has become a bottleneck for Monte-Carlo event simulation campaigns. We provide solutions to this problem by focusing on two major components of general-purpose event generators: The PDF evaluator and the matrix-element generator. For a typical production setup in the ATLAS experiment, we show that the two can consume about 80% of the total runtime. Using NLO simulations of  $$pp\rightarrow \ell ^+\ell ^-+\text {jets}$$  <math> <mrow> <mi>p</mi> <mi>p</mi> <mo>→</mo> <msup> <mi>ℓ</mi> <mo>+</mo> </msup> <msup> <mi>ℓ</mi> <mo>-</mo> </msup> <mo>+</mo> <mtext>jets</mtext> </mrow> </math>   and  $$pp\rightarrow t\bar{t}+\text {jets}$$  <math> <mrow> <mi>p</mi> <mi>p</mi> <mo>→</mo> <mi>t</mi> <mover> <mrow> <mi>t</mi> </mrow> <mrow> <mo>¯</mo> </mrow> </mover> <mo>+</mo> <mtext>jets</mtext> </mrow> </math>   as an example, we demonstrate that the computing footprint of Lhapdf and Sherpa can be reduced by factors of order 10, while maintaining the formal accuracy of the event sample. The improved codes are made publicly available.

Enrico Bothmann

Ilektra Christidi

Christian Gütschow

Stefan Höche

Max Knobbe

Tim Martin

Marek Schönherr

Accelerating LHC event generation with simplified pilot runs and fast PDFs

The evaluation of higher-order cross-sections is an important component in the search for new physics, both at hadron colliders and elsewhere. For most new physics processes of interest, total cross-sections are known at next-to-leading order (NLO) in the strong coupling  $$\alpha _s$$  <math> <msub> <mi>α</mi> <mi>s</mi> </msub> </math>  , and often beyond, via either higher-order terms at fixed powers of  $$\alpha _s$$  <math> <msub> <mi>α</mi> <mi>s</mi> </msub> </math>  , or multi-emission resummation. However, the computation time for such higher-order cross-sections is prohibitively expensive, and precludes efficient evaluation in parameter-space scans beyond two dimensions. Here we describe the software tool xsec, which allows for fast evaluation of cross-sections based on the use of machine-learning regression, using distributed Gaussian processes trained on a pre-generated sample of parameter points. This first version of the code provides all NLO Minimal Supersymmetric Standard Model strong-production cross-sections at the LHC, for individual flavour final states, evaluated in a fraction of a second. Moreover, it calculates regression errors, as well as estimates of errors from higher-order contributions, from uncertainties in the parton distribution functions, and from the value of  $$\alpha _s$$  <math> <msub> <mi>α</mi> <mi>s</mi> </msub> </math>  . While we focus on a specific phenomenological model of supersymmetry, the method readily generalises to any process where it is possible to generate a sufficient training sample.

Jon Sparre

Ingrid Vazquez-Holm

Xsec: the cross-section evaluation code

The Rivet library is an important toolkit in particle physics, and serves as a repository for analysis data and code. It allows for comparisons between data and theoretical calculations of the final state of collision events. This paper outlines several recent additions and improvements to the framework to include support for analysis of heavy ion collision simulated data. The paper also presents examples of these recent developments and their applicability in implementing concrete physics analyses.

Sweden

Denmark

Christian Bierlich

Christian Christensen

Peter Christiansen

Cody Duncan

Jan Grosse-Oetringhaus

Poland

Przemyslaw Karczmarczyk

Patrick Kirchgaeßer

Italy

Jochen Klein

Leif Lönnblad

Roberto Preghenella

Christine Rasmussen

Maria Stefaniak

Vytautas Vislavicius

Confronting experimental data with heavy-ion models: Rivet for heavy ions

We perform a phenomenological study of Z plus jet, Higgs plus jet and di-jet production at the Large Hadron Collider. We investigate in particular the dependence of the leading jet cross section on the jet radius as a function of the jet transverse momentum. Theoretical predictions are obtained using perturbative QCD calculations at the next-to and next-to-next-to-leading order, using a range of renormalization and factorization scales. The fixed order predictions are compared to results obtained from matching next-to-leading order calculations to parton showers. A study of the scale dependence as a function of the jet radius is used to provide a better estimate of the scale uncertainty for small jet sizes. The non-perturbative corrections as a function of jet radius are estimated from different generators.

Johannes Bellm

Switzerland

Xuan Chen

Aude Ridder

Thomas Gehrmann

Nigel Glover

Alexander Huss

Joey Huston

Silvan Kuttimalai

Portugal

Joao Pires

Austria

Simon Plätzer

Emanuele Re

Jet cross sections at the LHC and the quest for higher precision

Searches for supersymmetric electroweakinos have entered a crucial phase, as the integrated luminosity of the Large Hadron Collider is now high enough to compensate for their weak production cross-sections. Working in a framework where the neutralinos and charginos are the only light sparticles in the Minimal Supersymmetric Standard Model, we use GAMBIT to perform a detailed likelihood analysis of the electroweakino sector. We focus on the impacts of recent ATLAS and CMS searches with  of 13 TeV proton-proton collision data. We also include constraints from LEP and invisible decays of the Z and Higgs bosons. Under the background-only hypothesis, we show that current LHC searches do not robustly exclude any range of neutralino or chargino masses. However, a pattern of excesses in several LHC analyses points towards a possible signal, with neutralino masses of  = (8–155, 103–260, 130–473, 219–502) GeV and chargino masses of  = (104–259, 224–507) GeV at the 95% confidence level. The lightest neutralino is mostly bino, with a possible modest Higgsino or wino component. We find that this excess has a combined local significance of $$3.3\sigma $$ <math><mrow><mn>3.3</mn><mi>σ</mi></mrow></math> , subject to a number of cautions. If one includes LHC searches for charginos and neutralinos conducted with 8 TeV proton-proton collision data, the local significance is lowered to 2.9$$\sigma $$ <math><mi>σ</mi></math> . We briefly consider the implications for dark matter, finding that the correct relic density can be obtained through the Higgs-funnel and Z-funnel mechanisms, even assuming that all other sparticles are decoupled. All samples, GAMBIT input files and best-fit models from this study are available on Zenodo.

Peter Athron

Jonathan Cornell

Ben Farmer

Julia Harz

Paul Jackson

Rose Kudzman-Blais

Andreas Petridis

Christopher Rogan

Abhishek Sharma

Combined collider constraints on neutralinos and charginos

We discuss the simplified likelihood framework as a systematic approximation scheme for experimental likelihoods such as those originating from LHC experiments. We develop the simplified likelihood from the Central Limit Theorem keeping the next-to-leading term in the large N expansion to correctly account for asymmetries. Moreover, we present an efficient method to compute the parameters of the simplified likelihood from Monte Carlo simulations. The approach is validated using a realistic LHC-like analysis, and the limits of the approximation are explored. Finally, we discuss how the simplified likelihood data can be conveniently released in the HepData error source format and automatically built from it, making this framework a convenient tool to transmit realistic experimental likelihoods to the community.

Matthew Citron

Brazil

Sylvain Fichet

Sabine Kraml

Wolfgang Waltenberger

Nicholas Wardle

The simplified likelihood framework

In Ref. (GAMBIT Collaboration: Athron et. al., Eur. Phys. J. C. arXiv:1705.07908 , 2017 ) we introduced the global-fitting framework GAMBIT. In this addendum, we describe a new minor version increment of this package. GAMBIT1.1 includes full support for Mathematica backends, which we describe in some detail here. As an example, we backend SUSYHD Â (Vega and Villadoro, JHEP 07:159, 2015 ), which calculates the mass of the Higgs boson in the MSSM from effective field theory. We also describe updated likelihoods in PrecisionBit and DarkBit, and updated decay data included in DecayBit.

Csaba Balazs

Torsten Bringmann

Marcin Chrząszcz

Jan Conrad

Jonathan M. Cornell

Lars A. Dal

Hugh Dickinson

Joakim Edsjö

Tomás E. Gonzalo

Abram Krislock

Johan Lundberg

James McKay

Gregory D. Martinez

Antje Putze

Joachim Ripken

Aldo Saavedra

Christopher Savage

South Korea

Seon-Hee Seo

Nicola Serra

Netherlands

Christoph Weniger

Sebastian Wild

GAMBIT: the global and modular beyond-the-standard-model inference tool

We study the seven-dimensional Minimal Supersymmetric Standard Model (MSSM7) with the new GAMBIT software framework, with all parameters defined at the weak scale. Our analysis significantly extends previous weak-scale, phenomenological MSSM fits, by adding more and newer experimental analyses, improving the accuracy and detail of theoretical predictions, including dominant uncertainties from the Standard Model, the Galactic dark matter halo and the quark content of the nucleon, and employing novel and highly-efficient statistical sampling methods to scan the parameter space. We find regions of the MSSM7 that exhibit co-annihilation of neutralinos with charginos, stops and sbottoms, as well as models that undergo resonant annihilation via both light and heavy Higgs funnels. We find high-likelihood models with light charginos, stops and sbottoms that have the potential to be within the future reach of the LHC. Large parts of our preferred parameter regions will also be accessible to the next generation of direct and indirect dark matter searches, making prospects for discovery in the near future rather good.

A global fit of the MSSM with GAMBIT